The supermarket plans to launch the service next month. Insiders say Asda Mobile will be available in dedicated areas in its stores that will be staffed by experts.
The supermarket is in the final stages of appointing agencies to handle the online and in-store elements of the launch.
Asda marketing director Rick Bendel, who has said he wants the supermarket to be seen as a 'common-sense retailer', hinted that it would enter the mobile market when he criticised the lack of transparency among retailers about their offers last month. He said it was up to Asda to 'make sense of complicated issues like mobile phones'.
Tesco Mobile was launched in conjunction with O2 in 2003 and has signed up about 1m consumers. The supermarket's broadband and home-phone services have a combined total of about 1.5m subscribers.
Asda refused to comment on the launch of the service.